In a cellular communication, a user equipment existing in a cell accesses a base station to perform communication, receives control information for exchanging data from a base station, and then transceives data with the base station. In particular, since the user equipment transceives data through the base station, in order to transmit data to another cellular user equipment, the user equipment transmits its data to the base station. Having received the data, the base station transmits the received data to another user equipment. Thus, since data can be transmitted through the base station in order for one user equipment to transmit data to another user equipment, the base station performs scheduling of channels and resources for the data transceiving and also transmits channel and resource scheduling information to each user equipment. Thus, in order to perform UE-to-UE communication through the base station, each user equipment needs channel and resource allocations to transceive data with the base station. Yet, according to the structure of D2D communication, one user equipment directly transceives signals with another user equipment, to which data shall be transmitted, without using a base station or a relay node.
If a device-to-device (hereinafter abbreviated D2D) communication for transceiving data in direct between user equipments is performed in a manner of sharing resources with the existing cellular network mentioned in the above description, a user equipment desiring the D2D (device-to-device) communication discovers a target user equipment and then confirms whether a counterpart user equipment accepts the D2D (device-to-device) communication through a request. However, a procedure for a user equipment desiring a D2D (device-to-device) communication to make a request for the D2D (device-to-device) communication to a counterpart user equipment, a channel for the same, information necessary to be transmitted for the same, a transmitting method for the sane and the like have not been defined yet.